In the past, seats have been constructed with a wide variety of mechanisms and arrangements configured to enable adjustment to improve comfort of seat occupants having a wide variety of shapes, sizes and weights. As discussed in the background section of commonly owned U.S. Pat. No. 8,052,213, various types of adjustable pneumatic and mechanical seat occupant support assemblies have been employed in the past that seek to provide adjustable support to the lumbar region of the back of a seat occupant to improve comfort. While many of these have proven to be very effective, improvements nonetheless remain desirable.
Pneumatic lumbar adjustment assemblies tend to be complicated, expensive and often require a significant amount of space, including in certain instances space off-board the seat, to implement. Pneumatic assemblies typically require many additional costly components including an air bladder located inside the seat that is connected by tubing to controls manipulable by a seat occupant to operate an air pump to inflate the bladder when it is desired to increase lumbar support, and to deflate the bladder when it is desired to decrease lumbar support. Cheaper pneumatic assemblies typically employ a manually operated control valve, such as an inline needle-type valve, which can be opened to deflate the bladder and closed before a manual squeeze bulb pump is used to inflate the bladder. More expensive pneumatic assemblies require electrical power and control switches and/or valves to operate an electrically powered pump or air compressor that can and typically does charge one or more pneumatic compressed air storage cylinders during use and operation.
While cheaper, mechanical lumbar adjustment assemblies also tend to be complicated and often require many parts which undesirably increases assembly time and costs. Mechanical assemblies have long used flexible beam springs made of metal, e.g., spring steel, or plastic and are operated using complicated and costly actuating mechanisms including cable, clutch-connecting rod, and slow-to-adjust screw mechanisms. In addition to being complicated and costly, these lumbar adjustment assembly actuating mechanisms unfortunately impose significant limitations on seat designers as they inherently limit the number of locations where the controls a seat occupant uses to operate them can be located.
While many of these adjustable seat occupant support assemblies have enjoyed commercial success in the past, their complexity, cost and other limitations has limited more widespread application. As a result, adjustable lumbar supports remain an optional and costly accessory such that they are typically included only on a minority of seating products.